Motor-driven threading tool



Nov. 20, 1928.

E. L, CONNELL MOTOR DRIVEN THREADING TOOL Filed Aug. 10, 1925 v 50 for securing rotation .Of t

I Patented Nov. 20, '1928. I I

UNITED STATES I 1,692,487 PATIENT. OFFICE.

Erwin IL.ICONNEL L, or CLEVELAND, OHIO, ass-xenon TO THE van norm ELECTRIC 'rooL "COMPANY, or CLEVELAND, OHIO, A CORPORATION or OHIO.

MOTOB-DRIVEN THBEADIN G TOOL.

jilpplication filed August 10,. 1925. -Seria1'1 To. 49,339.

This invention relates to motor driven threading tools, such as are used for threading pipe or the like.

The object of the invention is to. provide an 5 improved device of the character described which is provided with simple and efiici'ent means for securing the necessary speed reduction, a proper forward speed for the threading operation and a more rapid speed for the reverse orvtool withdrawing operation, as well as an arrangement of the parts which is relatively simple and capable of convenient control, all without undue complication. In the drawings, Fig. 1 represents a side elevation, partly broken out and in section on the line 11, Fig. 2; and Fig. 2 is aneiid view, partly in section on the line 2'-2, Fig. 1.

While the apparatus may be built instationary form, for simplicity of illustration and as one preferred embodimentthe invention has been shown applied to a'portable hand tool adapted for use in threading pipe or the like. The tool shown includes a frame or casing 1, usually made of several parts suitably secured together, and in one end portion of which, marked 2, is located a suitable driv ing electric motor (not shown) for operating the motor shaft 3 provided with a inion- 4. At the opposite end of the casing is ocated a 3 hollow shaft 5 having keyed thereto a bevel gear 6, said' shaft being suitably journalled in the casing and provided atone end with adjustable guides and suitable operating means therefor, such as the scroll 8. At the opposite end said shaft is provided. with means for supporting thereon the threading tool or cutters, such as a head 9 sleeved over the end of the shaft 5 and removably secured thereon by the pin 10 and carrying sockets in which are located the threading cutters 11, although obviously any other threading tool or cutters could be employed, such 'asa tap for internal threads. At the extreme ends of the casing arelocated alined handles 1" for holding and manipulating the tool, in one of which is the switch operating handle 1.

Between the motor and the ,tool shaft 5 is located the gear mechanism for both securing the very necessary great s ed reduction and e tool shaft in opposite directions;

Electric motors of the t used in tools of this kind rotate at relative high speed, say at about 1.4000 R1. M. un erno' load and at about7000 R. P. M. at full load, The normal relation between gears 14 and 20. The purpose of longitudinal motion of said shaft is to secutting speed should be about 7 R. P. M.,so that a gear reduction of about 1000 to 1 is necessary, ordinarily requiring a very-extensive chain of reducing gears. In additiomto this, proper operation requires not only a forward cutting speed of 7R. P. M., but it is also desirable to reverse the direction of rotation of the tool shaft to withdraw the tool from the work, and preferably also the with drawing speed should be greater than the cutting speed, say at about 25 or more R. P. M. To this end and to simplify the necessary mechanism, I have taken advantage of differential gearing, as will more fully appear. The pinion- 4 on the motor shaft 3 drives a larger gear 12 on a jack shaft 13 carrying an elongated gear 14 meshing with a gear 15 fast with a bevel gear 16, both gears 15, 16 rotating on a through spindle 17 carrying the block 18 and which spindle 17 at its opposite end is rovided with a bevel gear 19 driving the vel gear 6 on the tool shaft 5 before referred to. Gear. 14 also drives a gear 20 of like diameter on a second jack shaft 21 slidable longitudinally in suitable bearings in the frame and provided with two gears rotating therewith, to wit, a large gear 22 and a small gear 23, the shaft 21 being provided with a grooved collar 24 to receive the fork of an operating lever 25, the handle 26 of which extends to the outside ofthe casing. By operating this handle the shaft 21 may be moved longitudinally back and forth without disturbing the driving lectively mesh either of the gears 22, 23 with one or the other of their mating gears 27, 28,

- which are fixed together and to a bevel gear 29 and rotate upon the forward end of the spin dle 17. The diflerentialbox gear including the two gears 16, 2,9 is completed by the two idle gears 30, 31, located on opposite sides of the block 18 and journalled on pins or stub shafts 32 thereon.

With the arrangement of gearing described, it will be obvious that if the motor rotates in the .fclockwise direction looking toward the bottom of Fig. 1, gear-15 will rotate in like direction and gears 27 and 28 in the opposite direction. The parts are so proportioned that the gear ratios between the three pairs of gears, 1e, 15in the first place, 22, 27 in the secondiplace and 23,28 in the third place, are such that when gears 22, 27 are in mesh, as shown in the drawings, gear 27 rotates in the opposite direction from gear 15 and at a greater speed, thereby producing through the action of the differential gears 16; 29, 30, 31,

counter-clockwise direction looking at the bottom of Fig. 1. Since the tool is applied to the pipe guide end first, so that the pipe being threaded extends out to the left in Fig. 1, it will be clear ,that the gears 22, 27 are the withdrawing pair of gears and produce reverse rotation of the tool spindle at a speed equal to the differential between the ratio of the second pair of gears 22, 27 and the ratio of the first pair of gears '14, 15.

WVhen the handle 26 is thrown to its opposite position to couple the gears 23, 28 the gear 28 rotates in the opposite direction from the gear 15, but at a slower speed, as a consequence of which the spindle 17 is again rotated in the direction of rotation of the faster moving gear, to wit, gear 15, and at a speed equal to the differential between the ratio of the third pair of gears 23, 28 and the ratio of the first pair of gears 14, 15. The gear sizes are preferably chosen with gear ratios such that the forward or cutting speed is at about 7 R. P. M. and the reverse or tool withdrawing speed is at about 25 R. P. M., more or less.

The arrangement described avoids the ordinary necessity not only for a fairly extensive chain of reducing gears to secure a speed reduction of approximately 1000 to 1, but also avoids a separate set'of reversing gears to change the direction of rotation of the tool spindle and at the same time secures slow forward or cutting speed and rapid tool withdrawal.

Other arrangements are suitable for the purpose than those shown in the drawings.

WVhat I claim is:

1. Thread cutting apparatus, comprising a tool rotating shaft carrying differential mechanism including two opposed gears, a driving shaft arranged in substantially parallel relation with said tool shaft, means where-- by said driving shaft rotates one of said gears at fixed speed in one direction, and means whereby said driving shaft also rotates thev opposed gear at a different speed. a positive rotation of spindle 17 in the 2. Thread cutting apparatus, comprisinga toolrotating shaft" carrying differential mechanism including two opposed gears, a driving shaft arranged in substantially parallel relation with said tool shaft, means whereby said driving shaft rotates one of said gears at fixed speed in one direction, and means whereby said driving shaft also rotates the opposed gear at two different speeds.

3. Thread cutting apparatus, comprising a tool rotating shaft carrying differential mechanism including two opposed gears, a driving shaft arranged in substantially parallel relation with said tool shaft, means whereby said driving shaft rotates one of said gears at fixed speed in one direction, and means whereby said driving shaft also rotates'the opposed gear at two different speeds, one greater and the other less than that of the first named gear.

4. Thread cutting apparatus, comprising a tool rotating shaft carrying differential mechanism including two opposed gears, a driving shaft arranged in substantially parallel relation with said tool shaft, means whereby said driving shaft rotates one of said gears at fixed speed in one direction, and means whereby said shaft also rotates the opposed gear at two different speeds, one greater than that of the first named gear.

5. Thread cutting apparatus, comprising a tool rotating shaft carrying differential mechanism including two opposed gears, a driving shaft arranged in substantially parallel relation with said tool shaft, means whereby said driving shaft rotates one of said gears at fixed speed in one direction, and means whereby said shaft also rotates the opposed gear at two different speeds, one less than that of the first named gear.

In testimony whereof I hereby afiix my signature.

EDWIN L. OONNELL. 

